n = int(input())
l = input()

rs = l.count("R")
print(l[:rs].count("W")) n = int(input()) n int(input()) int input() input l = input() l input() input rs = l.count("R") rs l.count("R") l.count l count "R" print(l[:rs].count("W")) print l[:rs].count("W") [:rs].count [:rs] l :rs rs count "W" l = input() input() l n = int(input()) int(input()) n rs = l.count("R") l.count("R") rs
n = int(input())
l = input()

rs = l.count("R")
print(l[:rs].count("W"))